Operation Hailstone

Operation Hailstone (known in Japan as Japanese: トラック島空襲 Torakku-tō Kūshū, lit. "the airstrike on Truk Island") was a massive naval air and surface attack launched on February 16–17, 1944, during World War II by the United States Navy against the Japanese naval and air base at Truk in the Caroline Islands, a pre-war Japanese territory.

Background

1944 US newsreel about the attack

Truk was a major Japanese logistical base as well as the operating "home" base for the Imperial Japanese Navy's Combined Fleet. Some have described it as the Japanese equivalent of the US Navy's Pearl Harbor. The atoll was the only major Japanese airbase within range of the Marshall Islands and was a significant source of support for Japanese garrisons located on islands and atolls throughout the central and south Pacific. The base was the key logistical and operational hub supporting Japan's perimeter defenses in the central and south Pacific.

To ensure air and naval superiority for the upcoming invasion of Eniwetok Admiral Raymond Spruance ordered an attack on Truk. Vice Admiral Marc A. Mitscher's Task Force 58 had five fleet carriers (Enterprise, Yorktown, Essex, Intrepid, and Bunker Hill) and four light carriers (Belleau Wood, Cabot, Monterey, and Cowpens), embarking more than 500 planes. Supporting the carriers was a large fleet of seven battleships, and numerous cruisers, destroyers, submarines, and other support ships.

Fearing that the base was becoming too vulnerable, the Japanese had relocated the aircraft carriers, battleships, and heavy cruisers of the Combined Fleet to Palau a week earlier. However, numerous smaller warships and merchant ships remained in and around the anchorage and several hundred aircraft were stationed at the atoll's airfields.

Map of Caroline Islands

Attack

Japanese ammunition ship Aikoku Maru blowing up; the air crew which dropped the bomb was missing and believed to have been caught in the explosion. February 17, 1944

The U.S. attack involved a combination of airstrikes, surface ship actions, and submarine attacks over two days and appeared to take the Japanese completely by surprise. Several daylight, along with nighttime, airstrikes employed fighters, dive bombers, and torpedo aircraft in attacks on Japanese airfields, aircraft, shore installations, and ships in and around the Truk anchorage. A force of U.S. surface ships and submarines guarded possible exit routes from the island's anchorage to attack any Japanese ships that tried to escape from the airstrikes.

In total the attack sank three Japanese light cruisers (Agano, Katori, and Naka), four destroyers (Oite, Fumizuki, Maikaze, and Tachikaze), three auxiliary cruisers (Akagi Maru, Aikoku Maru, Kiyosumi Maru), two submarine tenders (Heian Maru, Rio de Janeiro Maru), three other smaller warships (including submarine chasers CH-24 and Shonan Maru 15), aircraft transport Fujikawa Maru, and 32 merchant ships. Some of the ships were destroyed in the anchorage and some in the area surrounding Truk lagoon. Many of the merchant ships were loaded with reinforcements and supplies for Japanese garrisons in the central Pacific area. Very few of the troops aboard the sunken ships survived and little of their cargoes were recovered. (Lindeman, 2005)

Maikaze, along with several support ships, was sunk by U.S. surface ships while trying to escape from the Truk anchorage. On 17 February 1944, while evacuating convoys to Yokosuka from Truk following Allied attack on Truk, Maikaze, the cruiser Katori, and the auxiliary cruiser Akagi Maru were sunk by gunfire from the cruisers Minneapolis, New Orleans, and the battleship New Jersey 40 miles (64 km) northwest of Truk (07°45′N 151°20′E). Maikaze herself was sunk with all hands on board. The survivors of the sunken Japanese ships reportedly refused rescue efforts by the U.S. ships.

The cruiser Agano, a veteran of the Raid on Rabaul and which was already en route to Japan when the attack began, was sunk by a U.S. submarine, Skate. Oite rescued 523 survivors from Agano and returned to Truk lagoon to assist in its defense with her anti-aircraft guns. She was sunk soon after by air attack with the Agano survivors still on board, killing all of them and all but 20 of Oite's crew.

Over 250 Japanese aircraft were destroyed, mostly on the ground. Many of the aircraft were in various states of assembly, having just arrived from Japan in disassembled form aboard cargo ships. Very few of the assembled aircraft were able to take off in response to the U.S. attack. Several Japanese aircraft that did take off were claimed destroyed by U.S. fighters or gunners on the U.S. bombers and torpedo planes.

The U.S. lost twenty-five aircraft, mainly due to the intense anti-aircraft fire from Truk's defenses. About 16 U.S. aircrew were rescued by submarine or amphibious aircraft (several Japanese, whose crew took them prisoner). A nighttime torpedo attack by a Japanese aircraft from either Rabaul or Saipan damaged Intrepid and killed 11 of her crew, forcing her to return to Pearl Harbor and later, San Francisco for repairs. She returned to duty in June, 1944. Another Japanese air attack slightly damaged the battleship Iowa with a bomb hit.

An aerial view of the airstrike at Truk can be seen in the U.S. Navy film The Fighting Lady.

One well-known pilot, U.S. Marine Corps ace Gregory "Pappy" Boyington, survived this raid while being held prisoner on Truk, after being captured at Rabaul.

Aftermath

The attacks for the most part ended Truk as a major threat to Allied operations in the central Pacific; the Japanese garrison on Eniwetok was denied any realistic hope of reinforcement and support during the invasion that began on February 18, 1944, greatly assisting U.S. forces in their conquest of that island.

The Japanese later relocated about 100 of their remaining aircraft from Rabaul to Truk. These aircraft were attacked by U.S. carrier forces in another attack on April 29–30, 1944 which destroyed most of them. The U.S. aircraft dropped 92 bombs over a 29-minute period to destroy the Japanese planes. The April 1944 strikes found no shipping in Truk lagoon and were the last major attacks on Truk during the war.

Truk was isolated by Allied (primarily U.S.) forces as they continued their advance towards Japan by invading other Pacific islands such as Guam, Saipan, Palau, and Iwo Jima. Cut off, the Japanese forces on Truk, like on other central Pacific islands, ran low on food and faced starvation before Japan surrendered in August 1945.

Truk IJN Anchorage Evacuation Log Book

Oct 31, 1943 Truk -> Yokosuka
BB Yamashiro
BBV Ise
CVL Jun'yo
CVE Unyō
CA Tone
DD Tanikaze
DD Suzukaze
DD Umikaze

Nov 28, 1943 Truk -> Yokosuka
CVL Zuihō
CVE Unyō
CVE Chūyō
CA Maya
DD Akebono
DD Sazanami
DD Ushio
DD Urakaze

Dec 1, 1943 Truk -> Sasebo
BB Haruna
BB Kongō
DD Maikaze
DD Nowaki

Dec 7, 1943 Truk -> Kure
CV Zuikaku

Dec 7, 1943 Truk -> Yokosuka
CVL Chitose
DD Yukikaze
Food supply ship Irako

Dec 12, 1943 Truk -> Yokosuka
CV Shōkaku

Jan 1, 1944 Truk -> Yokosuka
DD Asakaze
Escort Manju
Cable layer Hashima
Minesweeper W-24
Yamabiko Maru
Yamakuni Maru
Keiyo Maru

Jan 10, 1944 Truk -> Sasebo
BB Yamato
DD Michishio
DD Asagumo
DD Fujinami

Jan 18, 1944 Truk -> Yokosuka
CVL Zuihō
CVE Unyō
DD Hatsushimo
DD Wakaba

Jan 19, 1944 Truk -> Saipan
DD Umikaze

Jan 19, 1944 Truk -> Rabaul
Kokuyo Maru
DD Maikaze

Jan 20, 1944 Truk -> Ponape
DD Hamanami
Escort CH-39
Escort CH-24
Escort CH-30
Escort CH-33
Ogura Maru No. 3

Jan 24 Truk -> Eniwetok
DD Suzukaze

Jan 25, 1944 Truk -> Saipan
CVE Unyō
DD Akebono
DD Ushio
Food supply ship Irako

Jan 27 Truk -> Yokosuka (convoy No. 4127)
Escort Fukue
Minesweeper W-23
Auxiliary subchaser Shonan Maru No. 8
Matsue Maru
Shinyo Maru
Yoshida Maru No. 3

Jan 28 Truk -> Rabaul
Hikawa Maru

Feb 1, 1944 Truk -> Palau
BB Nagato
BB Fusō
CA Kumano
CA Suzuya
CA Tone
DD Akizuki
DD Isokaze
DD Tanikaze
DD Hamakaze
DD Urakaze

Feb 3, 1944 Rabaul -> Truk => Beppu
Hikawa Maru

Feb 3, 1944 Yokosuka -> Truk
CVL Zuihō

Feb 5, 1944 Truk -> Davao
DD Ikazuchi

Feb 9, 1944 Truk -> Saipan (convoy No. 7125)
Escort Hirado
Reiyo Maru
Hanagawa Maru

Feb 10, 1944 Truk -> Palau
CA Atago
CA Chōkai
CA Haguro
CA Myōkō
DD Isokaze
DD Urakaze
DD Hamakaze
DD Tanikaze

Feb 10, 1944 Truk -> Yokosuka
BB Musashi
CL Ōyodo
CVL Chiyoda
CVL Zuihō
DD Wakaba
DD Hatsuharu
DD Shiratsuyu
DD Michishio
DD Tamanami

Feb 12, 1944 Truk -> Palau (convoy No. 7125)
DD Hamanami
Auxiliary subchasers Takunan Maru No. 2
Auxiliary subchasers Shonan Maru No. 5
Subchaser CH-30
Fleet oiler Sata
Tanker Hishi Maru No. 2
Ammunition ship Nichiro Maru
Cargo ship Kamikaze Maru
Cargo ship Kitakami Maru

Feb 13, 1944 Truk -> Yokosuka (convoy No. 4212)
Escort Manju
Escort Oki
Subchaser CH-31
Fleet supply ship Irako
Fleet supply ship Tatsuura Maru
Fleet supply ship Hibi Maru
Fleet oiler Notoro

Feb 13, 1944 Truk -> Kure
CVE Kaiyo
DD Hibiki
DD Inazuma

Feb 15, 1944 Truk -> Japan
CL Agano, sunk 160 miles norh of Truk on Feb 16th
DD Oite, sunk while entering back Truk via North Pass with survivors from CL Agano on Feb 18th
subchaser Ch-28, sunk on Feb 16th

Feb 15, 1944
DD Yamagumo
DD Nowaki
Asaka Maru

Feb 17, 1944 -> Truk
DD Fujinami
Minelayer Natsushima
Ryuku Maru

Feb 17, 1944 Truk -> Palau
DD Shigure
DD Harusame

Feb 17, 1944 Truk -> Yokosuka
CL Katori, sunk
DD Maikaze, sunk
DD Nowaki, the only ship escaped
Akagi Maru, sunk
Shonan Maru #15, sunk

Feb 17, 1944 Truk -> Yokosuka
DD Nowaki
DD Yamagumo
Asaka Maru

Feb 17, 1944 Truk -> assist damaged Agano
CL Naka, sunk

Feb 18, 1944 Truk -> Saipan
Tenno Maru

Feb 18, 1944 Truk -> Palau
Akitsushima

Feb 20, 1944 Truk -> Palau
DD Fujinami
DD Akikaze
Akashi

Feb 26, 1944 Truk -> Palau
Hikawa Maru

Feb 27, 1944 in Truk
Subchaser CH-38 complete battle-damage repairs
Subchaser CH-37 complete battle-damage repairs

Feb 29, 1944 -> Truk
Aratama Maru

Mar 6, 1944 Truk -> Saipan (convoy 4304)
Subchaser CH-33
Escort Amakusa
Escort Mikura
Minesweeper W-21
Urakami Maru
Shinane Maru
Juzan Maru

Mar 17, 1944 Truk -> Saipan (convoy 4304)
Escort Oki
Sub tender Tsukushi Maru
Kazuura Maru
Imizu Maru
Minelayer Yurishima

April 27, 1944 Truk -> Palau
Hikawa Maru

May 25, 1944 Truk -> Saipan
Ten'o Maru

June 3, 1944 Truk -> Saipan
Subchaser CH-32
Subchaser CH-20
Subchaser CH-31
Subchaser CH-51
Escort CD-6
Auxiliary subchaser CHa-66
Moji Maru
Imizu Maru
Tatsutagawa Maru
Kojun Maru
Oiler Nitcho Maru
Oiler Kyoei Maru
Oiler Nanko Maru No. 1
13 other unidentified ships.

List of warships in Truk at the time of attack

CL Agano (阿賀野) 6,652 tons, sunk on Feb 16th, 1944
CL Naka (那珂) 5,195 tons, departed to assist CL Agano and sunk 35 mile west of Truk on Feb 17th
CL Katori (香取) 5,890 tons, sunk 40 miles northwest of Truk on Feb 17th together with Maikaze and Shonan Maru #15, only Nowaki escaped
DD Akikaze (秋風) 峯風型 1,215 tons, escaped undamaged
DD Fumizuki (文月) 睦月型 1,315 tons, anchored in repair anchorage and sunk off west of lagoon on Feb 18th despite assistance from Matsukaze and Hakachi
DD Harusame (春雨) 白露型 1,685 tons, minor damage and later escorted damaged DD Shigure from Truk to Palau
DD Maikaze (舞風) 陽炎型 2,490 tons, sunk by gunfire northwest of Truk in convoy to Yokosuka on Feb 17th
DD Matsukaze (松風) 神風型 1,400 tons, assisted and attempted to tow DD Fumizuki, medium damage
DD Nowaki (野分) 陽炎型 2,490 tons, undamaged
DD Oite (追風) 神風型 1,270 tons, sunk while entering Truk via North Pass with survivors from CL Agano on Feb 18th
DD/P34 Susuki (薄) 樅型 935 tons, escaped but later sunk in an unrelated event off repair anchorage
DD Shigure (時雨) 白露型 1,685 tons, damaged while departing Truk via North Channel to Palau on Feb 17th
DD Tachikaze (太刀風) 峯風型 1,215 tons, ran aground on Kuop Atoll on Feb 4th and later sunk in Operation Hailstone

Auxiliary cruiser Akagi Maru (赤城丸) 7,367 tons, sunk north of Truk
Auxiliary submarine tender Heian Maru (平安丸) 11,616 tons, sunk off repair anchorage
Aircraft transport Fujikawa Maru (富士川丸) 6,938 tons, sunk off 4th fleet anchorage
Repair ship Akashi (明石) 10,500 tons, damaged
Seaplane tender Akitsushima (秋津洲) 4,650 tons, damaged

Submarine chaser CH-24, 438 tons, sunk west of Truk
Submarine chaser CH-28, 438 tons, departed Truk with destroyer Oite and cruiser Agano on 15th of Feb
Submarine chaser CH-33, 438 tons, damaged
Submarine chaser CHa-20, damaged
Submarine chaser CH-29, 420 tons, sunk
Auxiliary submarine chaser Shonan Maru #15 (第15昭南丸), sunk
Submarine I-10 (伊10), 2,919 tons, damaged
Submarine RO-36, 1,115 tons, damaged
Submarine RO-42, 1,115 tons, undamaged
Motor torpedo boat #10, 80 tons, sunk
Cargo ship Sōya (宗谷) 3,800 tons, damaged
Target ship Hakachi (波勝) 1,641 tons, damaged

List of merchant ships at the time of attack and other shipwrecks in Truk's Anchorage

Navy transport Aikoku Maru (爱国丸) 10,348 tons, sunk off 4th fleet anchorage
Navy transport Kiyosumi Maru (清澄丸) 6,983 tons, sunk off repair anchorage
Navy transport Rio de Janeiro Maru (りおで志゛やねろ丸) 9,627 tons, sunk off 6th fleet anchorage
Navy transport Yamagiri Maru (山霧丸) 6,439 tons, carrying Yamato's 46 cm projectiles, sunk off combined fleet anchorage
Navy transport/passenger/cargo ship Kensho Maru (乾祥丸) 4,861 tons, sunk off repair anchorage
Navy transport/passenger/cargo ship Sankisan Maru (山鬼山丸) 4,776 tons, sunk off 6th fleet anchorage
Navy transport Houki Maru (伯耆丸) 7,112 ton, sunk off 4th fleet anchorage
Navy transport Reiyo Maru (麗洋丸) 5,446 tons,sunk off 4th fleet anchorage
Navy transport/freighter Syoutan Maru (松丹丸) 1,999 tons, sunk off 4th fleet anchorage
Navy water carrier/passenger/cargo ship Nippo Maru (日豊丸) 3,673 tons, sunk off 4th fleet anchorage
Navy transport Taiho Maru (大邦丸) 2,829 tons,sunk off 6th fleet anchorage
Navy transport/freighter Gosei Maru (五星丸) 1,931 tons, sunk off 6th fleet anchorage
Navy transport/freighter Hanakawa Maru (花川丸) 4,793 tons, sunk off Tol
Navy transport/freighter Hokuyo Maru (北洋丸) 4,217 tons, sunk off 4th fleet anchorage
Navy transport/freighter Momokawa Maru (桃川丸) 3,829 tons, sunk off 4th fleet anchorage
Navy transport/freighter San Francisco Maru (桑港丸) 5,864 tons, sunk off 4th fleet anchorage
Navy transport/freighter Unkai Maru #6(第六雲海丸) 3,188 tons, sunk off 6th fleet anchorage
Navy transport Kikukawa Maru (菊川丸) 6,853 tons, accidentally sunk on Oct 7th, 1943
Navy transport Saiko Maru (西江丸)? 5,385 tons,sunk on Feb 17th, 1944
Navy hospital ship Ten'o Maru (天應丸) 6,067 tons, anchored next to Heian Maru, escaped
Navy transport Zukai Maru (瑞海丸) 2,812 tons, escaped
Navy transport Tatsuhane Maru (辰羽丸), also known as Tatuha Maru, 5,784 tons, escaped
Freighter Katsuragisan Maru (葛城山丸) 2,428 tons, sunk on Jan 4th 1944 north east off Moen
Freighter Matsutani Maru (松谷丸)? 1,999 tons
Freighter Taikichi Maru (泰吉丸)?
Freighter Hino Maru #2 (第二日野丸) 999 tons, sunk off the 6th fleet anchorage near Uman Island
Freighter Seiko Maru (星光丸)? 5,386 tons, sunk

Army transport Gyoten Maru (暁天丸) 6,865 tons, sunk by USS Tang off Truk on February 17, 1944
Army transport Yubae Maru (夕映丸) 3,200 tons,sunk off 6th fleet anchorage
Army transport/freighter Nagano Maru (長野丸) 3,810 tons, sunk off 4th fleet anchorage

Fleet oiler Shinkoku Maru (神国丸) 10,020 tons, sunk off combined fleet anchorage
Oil tanker Fujisan Maru (富士山丸) 9,524 tons, sunk south west off Moen
Auxiliary oil tanker Houyou Maru (宝洋丸) 8,691 tons, sunk off repair anchorage
Auxiliary oil tanker/passenger/cargo ship Amagisan Maru (天城山丸) 7,620 tons, sunk off 6th fleet anchorage
Auxiliary oil tanker/whaler Tonan Maru #3 (第三図南丸) 19,209 tons, sunk off repair anchorage
Auxiliary provision storeship Sapporo Maru (札幌丸), sunk on May 29, 1944 on west of lagoon
Repair ship/cargo ship Urakami Maru, anchored next to Tenno Maru and Heian Maru, damaged

Picket boat Kotohira Maru 30 tons, sunk on April 15, 1944
Salvage tug Woshima (雄島) 812 tons, accidentally sunk in an explosion with Kikukawa Maru on Oct 7th,1943
Salvage tug Futakami (二神) 600 tons, scuttled off repair anchorage postwar

Further reading

• -Firsthand account of Operation Hailstone by a crewmember of USS New Orleans.
• Tashirō Iwashige, The visual guide of Japanese wartime merchant marine, (Japan), May 2009. ISBN 978-4-499-22989-0

Video

• Quest for Sunken Warships : "Operation Hailstone", 2007, documentary, Military Channel, last aired September 30, 2010, 4-5pm MDT.

External links

• WW2DB: Attack on Truk
• Account of the operation from Enterprise website
• Moderately brief account of the attack
• TRUK LAGOON AREA STUDY